1. Field of the Invention
The present invention relates in general to methods for making akanol- or alkane-sulfone plumbates used for lead plating and solder plating applications, and relates in particular to a method for making alkanol- or alkane-sulfone plumbates using lead oxide compounds as feed material, which have been regarded as difficult to dissolve in alkanol-sulfonic acid or alkane-sulfonic acid.
2. Description of the Related Art
For work involving lead plating and solder plating containing lead, acidic plating solutions based on alkanol-sulfonic acid or alkane-sulfonic acid are used. The alkanol-sulfonic or alkane-sulfonic plumbates are usually used as source of lead in such cases.
Conventionally, alkanol-sulfonic or alkane-sulfonic plumbates, in particular low .alpha.-rays radiation alkanol-sulfonic or alkane-sulfonic plumbates are generally made by reacting alkanol-sulfonic acid or alkane-sulfonic acid on metallic lead. However, it is desirable to make such materials by using naturally existing lead oxides.
Particularly, it is known in recent years that a-rays radiation emitted from lead contained in soldered products causes malfunction of electronic devices. Since then, alkanol-sulfonic or alkane-sulfonic plumbates have been made by using materials of low .alpha.-rays radiation lead oxide compounds. However, the volume of production of low radiation lead compounds is relatively small, and the production is tight for supplying thereto to satisfy the demand.
On the other hand, lead oxide such as Pb.sub.3 O.sub.4 and PbO.sub.2 are difficult to dissolve in alkanol-sulfonic acid and alkane-sulfonic acid, and they have not been considered as feed materials for making alkanol-sulfonic or alkane-sulfonic plumbates. However, as the availability of low-radiation lead compounds becomes more difficult, there has been required for a method of making low-radiation alkanol-sulfonic or alkane-sulfonic plumbates by using such lead oxide compounds.